Black bear encounters happen every summer in Alaska, and a new study suggests rubber bullets are the best way to send the bruins packing.
An article in this month's issue of The Journal of Wildlife Management based on a four-year study in California's Sequoia National Park says shooting black bears with rubber slugs from a 12-gauge shotgun is most effective -- better than pepper spray, chasing them off or hitting them with rocks. Researchers detailed 1,050 instances of so-called aversive conditioning on more than 150 bears, some of which had become accustomed to human food.
"It confirms everything we've been saying for decades about black bears and garbage," said Rick Sinnott, Anchorage area biologist with the Alaska Department of Fish and Game. "(But) chasing and rock throwing are cheaper and within the means of most of the adult residents of the city."
Aversive conditioning aims to link humans with something bad or painful that happen to the bears. Park officials yelled at the bears during most encounters to reinforce the conditioning.
Such conditioning was most effective, researchers found, when done immediately after a bear's first contact with human food.
"Those shot with rubber slugs or chased were about twice as likely to run away as those given moderate treatments (rocks, slingshots) or pepper sprayed," wrote Rachel Mazur of the Sequoia and Kings Canyon national parks in California, who authored the report. "Among the 36 food-conditioned bears, rubber slugs had far more immediate success than other treatments, causing animals to run away 92 percent of the time. Every other treatment caused bears to run in fewer than half of the trials."
And just like humans, only a handful of the bears got in most of the trouble. Eleven of the 150 bears accounted for 90 percent of the incidents. Six bears were either killed or relocated for safety reasons during the study period.
But nothing researchers did overpowered the bears' drive to find food -- whether natural food or human food and garbage in developed areas. The study noted that in areas where bears require access to critical habitats, it may be best to seasonally exclude people rather than bears from areas rife with potential conflicts.
Last August in Muldoon, a black bear was killed by a man with a .44-caliber magnum handgun.
"The source was certainly garbage," Rick Sinnott, a biologist with the Alaska Department of Fish and Game, said at the time. "The bear was coming back over the fence for, I'm sure, more garbage. It wasn't hunting people, it was after garbage. There was a threat in someone's mind and someone with a gun showed up and the bear didn't immediately take off."
Alaska law allows people to kill bears in defense of life or property.
Fish and Game estimates there are about 250 black bears in Anchorage between the Knik River and Portage. Every year since 2004, at least 10 Anchorgage black bears have been shot every year in defense of life and property. The 21 shot in 2008, the all-time high, was nearly cut in half the following year, when 11 were shot.
"The number of bears in the Anchorage area has increased in the last two decades," Fish and Game says on its Web site, "primarily because hunting has been restricted. Bears are entering residential areas in increasing numbers to eat garbage, dog food and bird seed -- and are becoming bolder in obtaining it."
Applying aversive conditioning early and consistently can be difficult in an urban setting like Anchorage.
"The take-home message is that hazing is expensive and only temporarily effective," Sinnott said. "It works best on bears before they've become food-conditioned. The single-best way to avoid problems with black bears in Anchorage is to control access to garbage and other human-provided foods."
Reach reporter Mike Campbell at mcampbell@adn.com or 257-4329.
By MIKE CAMPBELL
mcampbell@adn.com